US10829214B2 - Elastic torsion element for connecting a rotor blade to a rotor hub of a rotor - Google Patents

Elastic torsion element for connecting a rotor blade to a rotor hub of a rotor Download PDF

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Publication number
US10829214B2
US10829214B2 US16/143,774 US201816143774A US10829214B2 US 10829214 B2 US10829214 B2 US 10829214B2 US 201816143774 A US201816143774 A US 201816143774A US 10829214 B2 US10829214 B2 US 10829214B2
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elastically deformable
elastic
torsion element
elastic torsion
deformable plates
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US20190112040A1 (en
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Moritz BUESING
Rupert Pfaller
Martin Ortner
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Airbus Helicopters Deutschland GmbH
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Airbus Helicopters Deutschland GmbH
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Assigned to Airbus Helicopters Deutschland GmbH reassignment Airbus Helicopters Deutschland GmbH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BUESING, MORITZ, ORTNER, MARTIN, PFALLER, RUPERT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/46—Blades
    • B64C27/473—Constructional features
    • B64C27/48—Root attachment to rotor head
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/33—Rotors having flexing arms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/46—Blades
    • B64C27/473—Constructional features
    • B64C2027/4733—Rotor blades substantially made from particular materials
    • B64C2027/4736—Rotor blades substantially made from particular materials from composite materials

Definitions

  • the invention is related to an elastic torsion element for connecting a rotor blade to a rotor hub of a rotor.
  • the invention is further related to a rotary wing aircraft with a rotor that comprises such an elastic torsion element.
  • elastic torsion elements are used to connect rotor blades of a multi-blade rotor of a rotary wing aircraft to an associated rotor hub or shaft of the aircraft.
  • a respective elastic torsion element must withstand tremendous centrifugal forces that the rotor blades apply thereto, while permitting their flapping, pitch and lead-lag motions.
  • a flexbeam element is a special, in particular fiber reinforced composite material element that is flexible enough in bending without discrete hinges, in the case of a hingeless rotor system, or in bending and in torsion to allow twisting for blade movement without bearings, in the case of a bearingless rotor system.
  • a flexbeam element usually realizes a flapwise-soft region that enables flapping of the associated rotor blade in the vertical direction, i.e. rotation of the associated rotor blade out of the respective rotation plane defined by the given multi-blade rotor.
  • the flapwise-soft region constitutes a fictitious horizontally oriented axis, a so-called virtual flapping hinge, about which the associated rotor blade flaps, i.e. executes upward and downward flapwise motions in a bearingless or a hinge- and bearingless rotor system.
  • the flexbeam element only in a bearingless rotor system, the flexbeam element usually comprises a torsion weak region that enables torsion, i.e.
  • the flexbeam element usually possesses a lead-lag-soft region that permits motions of an associated rotor blade in a bearingless or a hinge- and bearingless rotor system in the lead-lag direction.
  • the lead-lag-soft region thus constitutes a fictitious vertically oriented axis, a so-called virtual lead-lag hinge, about which the rotor blade executes forward and backward lead-lag motions, i.e. rotation of the associated rotor blade within a respective rotation plane defined by a given multi-blade rotor.
  • the lead-lag-soft region and the torsion weak region are arranged between the flapwise-soft region and a respective rotor blade attachment, where the associated rotor blade is attached, or a transition zone into an aerodynamic profile that forms the associated rotor blade.
  • the lead-lag-soft region and a torsion weak region such that the lead-lag-soft region is integrated into the torsion weak region which is, preferably, resistant against excessive deformation and buckling deformation under flapping loads without additional supports, such as e.g. a specific flap stop. Consequently, such a torsion weak region with integrated lead-lag-soft region leads to transition from a shape with high lead-lag stiffness and low flapping stiffness into a shape with low lead-lag stiffness and high flapping stiffness, due to its arrangement between the flapwise-soft region and the respective rotor blade attachment.
  • respective flexbeam elements are usually rather complex and consist of composite components that are very elaborate and difficult to manufacture. Thus, these composite components are generally expensive.
  • each lead-lag and feathering portion has a central portion with an elongated and narrow width; middle portions each of which continuously connects to the central portion and branches from both ends of the central portion extending along the longitudinal direction thereof, and extends upward and downward; and edge portions each of which continuously connects to a respective middle portion and bends from each end of the respective middle portion and extends almost in parallel with the central portion. More specifically, each lead-lag and feathering portion has an at least approximately X-shaped cross-section. However, such a cross-section is complicated and elaborate to manufacture and, consequently, expensive, and provides for a comparatively high lead-lag stiffness.
  • an object of the present invention to provide a new elastic torsion element for connecting a rotor blade to a rotor hub of a rotor.
  • This new elastic torsion element should comprise an integrated elastic lead-lag hinge and should be manufacturable easily and at comparatively low cost.
  • an elastic torsion element for connecting a rotor blade to a rotor hub of a rotor, the elastic torsion element comprising the features of claim 1 .
  • an elastic torsion element for connecting a rotor blade to a rotor hub of a rotor comprises at least two elastically deformable plates.
  • Each one of the at least two elastically deformable plates comprises fiber reinforced polymers.
  • Respective fibers of the fiber reinforced polymers of each one of the at least two elastically deformable plates are at least arranged along one of a first and a second dominant fiber directions, wherein the first dominant fiber direction crosses the second dominant fiber direction in a predetermined fiber direction crossing region.
  • the elastic torsion element comprises an integrated elastic lead-lag hinge that is formed at the predetermined fiber direction crossing region.
  • the at least two elastically deformable plates are manufactured as composite plates using glass, basalt, carbon and/or aramid fiber fabrics and rovings that are oriented in different angles with respect to each other. More specifically, in order to enable transfer of comparatively high centrifugal forces and lead-lag as well as flapping bending moments, preferably most of the respective fibers are oriented within +/ ⁇ 15° with respect to a virtual line that is oriented in parallel to a respective pitching resp. torsion axis of the rotor blade.
  • preferably comparatively large roving plies are oriented in different directions between the +/ ⁇ 15° and cross each other in the predetermined fiber direction crossing region. This leads to a comparatively narrow section of the elastic torsion element at said predetermined fiber direction crossing region, where the large roving plies preferably overlap.
  • This comparatively narrow predetermined fiber direction crossing region has a comparatively low lead-lag bending stiffness according to one aspect and, thereby, defines the integrated elastic lead-lag hinge.
  • the elastic torsion element further defines an elastic flapping hinge area and the at least two elastically deformable plates become wider and thinner towards the elastic flapping hinge area, which is advantageous for a respective transition into a selected shape of the elastic flapping hinge area.
  • the elastic flapping hinge area preferably exhibits a comparatively high lead-lag stiffness and a comparatively low flapping stiffness.
  • the at least two elastically deformable plates also become wider and thinner towards an associated rotor blade attachment area, where the elastic torsion element is connected to the rotor blade.
  • the rotor blade attachment area can be implemented by an integrated transition area that transitions into an underlying aerodynamic profile that forms the rotor blade.
  • the elastic torsion element and, more specifically, the at least two elastically deformable plates exhibit curved, e.g. U-shaped cross-sections.
  • a respective shear center of such U-shaped cross sections is preferably close to the pitching resp. torsion axis of the rotor blade, respectively of the elastic torsion element.
  • an elastically deformable plate that is directly arranged at the pitching resp. torsion axis of the rotor blade preferably merely exhibits a point symmetric cross-sectional shape, e.g. a rectangular shape or an S-shape.
  • the U-shaped cross-sections can be created by smooth transitions from flat shapes, e.g. shapes that are provided in the elastic flapping hinge area and/or a respective rotor blade attachment area or transition area to the aerodynamic profile, with minimal bending of respective fibers within an underlying plane of the plies. Furthermore, by separating the cross-sections, i.e. each elastically deformable plate, into multiple separate plates, a corresponding torsion resistance of the elastic torsion element can be reduced further. Moreover, both the location of the shear centers and the separation into multiple elastically deformable plates reduce a corresponding Saint Vernant component of torsion stiffness.
  • the multiple elastically deformable plates form an overall cross-sectional shape that is similar to a star-shape, which is advantageous for low warping stiffness (a so-called “Wölbsteiftechnik”).
  • the curved U-shaped cross-sections exhibit comparatively high resistance against buckling.
  • the integrated elastic lead-lag hinge is arranged in an area of the inventive elastic torsion element that is clearly separated from other areas of the elastic torsion element, such as a respective elastic flapping hinge area, a rotor blade attachment area, or a respective transition area to an associated aerodynamic profile.
  • the integrated elastic lead-lag hinge exhibits a low lead-lag stiffness and a high flapping stiffness, i.e. at least a lead-lag stiffness that is smaller than the associated flapping stiffness.
  • the inventive elastic torsion element exhibits a comparatively low torsion stiffness and a comparatively high resistance against buckling under flapping loads.
  • overlapping areas of a respective torsion weak region and the integrated elastic lead-lag hinge are preferably provided.
  • each one of the elastically deformable plates can be manufactured by stacking separate plies vertically, with little or no bending of respective composite fibers within the plane of the plies.
  • the inventive elastic torsion element comprises four separate elastically deformable plates that form the integrated elastic lead-lag hinge.
  • Each one of these four elastically deformable plates is preferably implemented with two dominant fiber directions for respective fibers that are provided to transfer at least most of centrifugal forces as well as flapping and lead-lag bending forces that are applied to the elastic torsion element in operation.
  • the two dominant fiber directions preferably cross each other in the predetermined fiber direction crossing region, such that the inventive elastic torsion element is narrowest in the location where the two dominant fiber directions cross each other, and, therefore, overlap.
  • the two dominant fiber directions preferably diverge in order to form areas with only one dominant fiber direction.
  • the elastic torsion element is smoothed in selected areas by adding material with interrupted fibers.
  • composite layers with differing orientations and composite fabric layers are added in order to increase a respective in-plane shear stiffness of the inventive elastic torsion element.
  • a bearing laminate can be created that is suitable for application of e.g. bolts and/or rivets, and furthermore excessively thin sections can be avoided and reinforced against buckling.
  • the four elastically deformable plates are formed such that they transition from comparatively flat shapes that are embodied adjacent to a respective flapping hinge area of the elastic torsion element into U-shaped cross-sections in an effective area of the integrated elastic lead-lag hinge. Respective shear centers of these cross-sections are preferably close to an underlying pitching resp. torsion axis of the inventive elastic torsion element.
  • the inventive elastic torsion element has a comparatively easy design so that it can be manufactured easily and in a cost-effective manner. More specifically, it can preferably be embodied by using simple components, i.e. the elastically deformable plates, which are preferentially plate-, strip-, bar- and/or lath-shaped elastic members with simple rectangular cross-sections that may preferably even allow for connection to associated rotor blades with no need for a cross-section change.
  • Such plate-, strip-, bar- and/or lath-shaped elastic members may have a comparatively short length.
  • the plate-, strip-, bar- and/or lath-shaped elastic members are manufactured using fiber composite materials.
  • fiber reinforced polymers are used, such as carbon fiber reinforced polymers, glass fiber reinforced polymers, aramid fiber reinforced polymers or basalt fiber reinforced polymers.
  • the inventive elastic torsion element and, in particular, its integrated elastic lead-lag hinge preferably comprises two or more elastically deformable plates that are stacked on top of each other. Each one of the at least two elastically deformable plates preferably comprises fiber reinforced polymers.
  • the fiber reinforced polymers comprise carbon, glass, aramid and/or basalt fiber fabrics and rovings.
  • the respective fibers of the fiber reinforced polymers of each one of the at least two elastically deformable plates are at least essentially oriented within +/ ⁇ 15° with respect to a longitudinal axis of the elastic torsion element.
  • the respective fibers of the fiber reinforced polymers of each one of the at least two elastically deformable plates are at least arranged along one third dominant fiber direction that crosses at least one of the first dominant fiber direction and the second dominant fiber direction.
  • the at least two elastically deformable plates comprise at least a first and a second elastically deformable plate that exhibit at least approximately an arc-shaped cross-section in a respective elastic lead-lag hinge area of the integrated elastic lead-lag hinge.
  • the at least two elastically deformable plates comprise at least one third elastically deformable plate that is arranged between the first and second elastically deformable plates and exhibits a point symmetric cross-section in the respective elastic lead-lag hinge area.
  • the at least one third elastically deformable plate exhibits a rectangular cross-section in the respective elastic lead-lag hinge area.
  • the at least one third elastically deformable plate exhibits at least approximately an S-shaped cross-section in the respective elastic lead-lag hinge area.
  • the at least approximately arc-shaped cross-section in the respective elastic lead-lag hinge area of the integrated elastic lead-lag hinge transitions along a longitudinal axis of the elastic torsion element towards an elastic flapping hinge area into a flat cross-section.
  • the at least approximately arc-shaped cross-section in the respective elastic lead-lag hinge area of the integrated elastic lead-lag hinge transitions along a longitudinal axis of the elastic torsion element towards a rotor blade attachment area or transition zone into a flat cross-section.
  • the integrated elastic lead-lag hinge is formed by a narrowest cross-section area of the elastic torsion element.
  • the at least two elastically deformable plates comprise at least two upper elastically deformable plates and at least two lower elastically deformable plates, wherein the at least two lower elastically deformable plates are arranged in reflection symmetry to the at least two lower elastically deformable plates.
  • the at least two lower elastically deformable plates are attached to the at least two lower elastically deformable plates by means of a bolted connection, the bolted connection being provided at least approximately at a longitudinal axis of the elastic torsion element.
  • At least one first and one second elastically deformable plates of the at least two elastically deformable plates are integrated into a single slotted elastically deformable plate, wherein the at least one first and one second elastically deformable plates are at least partly separated in the single slotted elastically deformable plate by means of an associated separating slot.
  • the present invention further provides a rotary wing aircraft with at least one rotor that comprises at least two rotor blades, and with a rotor hub, each one of the at least two rotor blades being connected to the rotor hub via an elastic torsion element that is embodied as described above.
  • FIG. 1 shows a partially perspective top view of a multi-blade rotor having at least one elastic torsion element according to the invention
  • FIG. 2 shows a top view of a partial laminate of a selected one of the elastic torsion elements of FIG. 1 , comprising only uninterrupted fibers following dominant fiber directions,
  • FIG. 3 shows a top view of a full laminate of the elastic torsion element of FIG. 2 with the uninterrupted fibers, as well as with interrupted fibers and spliced plies,
  • FIG. 4 shows a cut view of the full laminate of FIG. 3 , seen along a cut line IV-IV in FIG. 3 ,
  • FIG. 5 shows a cut view of the full laminate of FIG. 3 , seen along a cut line V-V in FIG. 3 ,
  • FIG. 6 shows a top view of a partial laminate of an alternative elastic torsion element having uninterrupted fibers following dominant fiber directions
  • FIG. 7 shows a top view of a full laminate of the elastic torsion element of FIG. 6 with the uninterrupted fibers, as well as with interrupted fibers and spliced plies,
  • FIG. 8 shows a cut view of the full laminate of FIG. 6 , seen along a cut line VIII-VIII of FIG. 7 ,
  • FIG. 9 shows the cut view of FIG. 8 according to a first variant
  • FIG. 10 shows the cut view of FIG. 8 according to a second variant
  • FIG. 11 shows a partially perspective top view of a selected one of the elastic torsion elements of FIG. 1 , according to still another variant of the present invention.
  • FIG. 1 shows a multi-blade rotor 1 of a rotary wing aircraft, in particular a multi-blade rotor for a main rotor of a helicopter.
  • the multi-blade rotor 1 illustratively comprises a rotor shaft 8 that is embodied with a rotor hub 7 .
  • a rotor head covering cap 9 is provided for covering a central portion of the multi-blade rotor 1 , which comprises the rotor hub 7 and which illustratively defines an associated rotor head.
  • the rotor head covering cap 9 is shown with an illustrative cut-out 9 a , where the rotor head covering cap 9 is partially cut away in order to permit amongst others the illustration of the rotor hub 7 .
  • the multi-blade rotor 1 is preferably embodied as a bearingless rotor having a multiplicity of elastic hinge units 3 as interfaces between the rotor shaft 8 , i.e. the rotor hub 7 , and a plurality of rotor blades 2 a , 2 b , 2 c , 2 d , 2 e . It should, however, be noted that these rotor blades 2 a , 2 b , 2 c , 2 d , 2 e are not shown in greater detail, neither in FIG. 1 nor in the remaining figures, for simplicity and clarity of the drawings. Furthermore, it should be noted that the expression “multi-blade rotor” should be construed in the context of the present invention such that it encompasses all rotors having at least two rotor blades.
  • the multiplicity of elastic hinge units 3 preferably implements a multiplicity of elastic torsion elements 5 , i.e. elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e . It should, however, be noted that for simplicity and clarity of the drawings only a single elastic hinge unit of the multiplicity of elastic hinge units is designated with the reference number 3 and described representatively hereinafter for all elastic hinge units of the multiplicity of elastic hinge units, which are preferably at least similarly embodied.
  • the multiplicity of elastic hinge units defines a predetermined number of elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e of the multi-blade rotor 1 , such that each one of the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e is associated with a given rotor blade of the plurality of rotor blades 2 a , 2 b , 2 c , 2 d , 2 e .
  • the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e preferably comprise a plurality of hub connecting points 10 for connection to the rotor hub 7 .
  • each one of the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e preferably comprises one or more blade connecting points 3 a , 3 b , 3 c , 3 d , 3 e for connection to an associated one of the rotor blades 2 a , 2 b , 2 c , 2 d , 2 e .
  • the rotor blades 2 a , 2 b , 2 c , 2 d , 2 e are connected to the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e at the blade connecting points 3 a , 3 b , 3 c , 3 d , 3 e and can be disconnected therefrom, if required.
  • the rotor blades 2 a , 2 b , 2 c , 2 d , 2 e and the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e , i.e. the multiplicity of elastic hinge units 3 can also be implemented as integral components, so that they could not be disconnected from each other.
  • the blade connecting points 3 a , 3 b , 3 c , 3 d , 3 e merely define virtual transition points resp. transition zones to associated aerodynamic profiles that form the rotor blades 2 a , 2 b , 2 c , 2 d , 2 e.
  • Each one of the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e is preferably further associated with a control cuff of a multiplicity of control cuffs 6 , i.e. control cuffs 6 a , 6 b , 6 c , 6 d , 6 e .
  • control cuffs 6 a , 6 b , 6 c , 6 d , 6 e are preferably adapted for setting in operation of the multi-blade rotor 1 a current pitch or blade angle of the rotor blades 2 a , 2 b , 2 c , 2 d , 2 e by controlling a current torsion of the elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e , i.e. of the multiplicity of elastic hinge units.
  • control cuff 6 d is driveable for setting the current pitch or blade angle of the rotor blade 2 d by controlling the current torsion of the elastic torsion element 5 d , i.e. the current torsion of the elastic hinge unit 3 .
  • the elastic torsion element 5 d comprises at least an integrated elastic lead-lag hinge 4 that is illustratively provided for enabling lead-lag motions of the rotor blade 2 d relative to the rotor hub 7 .
  • the elastic torsion element 5 d may further comprise an elastic flapping hinge area ( 13 b in FIG. 2 ).
  • the elastic torsion element 5 d defines a longitudinal direction 5 f directed, by way of example, from the rotor shaft 8 to its blade connecting point 3 d.
  • FIG. 2 shows the elastic torsion element 5 d with the integrated elastic lead-lag hinge 4 of FIG. 1 .
  • the elastic torsion element 5 d has the longitudinal axis 5 f of FIG. 1 and is representatively illustrated for all elastic torsion elements of FIG. 1 .
  • all elastic torsion elements 5 a , 5 b , 5 c , 5 d , 5 e of the multi-blade rotor 1 of FIG. 1 are preferably identically formed, at least within usual predetermined manufacturing tolerances.
  • the elastic torsion element 5 d comprises a multiplicity of elastically deformable plates 11 . More specifically, the elastic torsion element 5 d preferably comprises at least two elastically deformable plates 11 a (and 11 b in FIG. 4 and FIG. 5 ). Illustratively, and due to a selected viewing direction in FIG. 2 , however, only the elastically deformable plate 11 a of the multiplicity of elastically deformable plates 11 is shown.
  • the elastic torsion element 5 d is only shown as partial laminate 20 , which illustratively only comprises uninterrupted fibers following predetermined dominant fiber directions.
  • the elastically deformable plate 11 a preferably comprises fiber reinforced polymers.
  • the fiber reinforced polymers comprise carbon, glass, aramid and/or basalt fiber fabrics and rovings.
  • respective fibers of the fiber reinforced polymers of the elastically deformable plate 11 a are preferably uninterrupted and selectively arranged along one of at least two dominant fiber directions 12 a , 12 b .
  • the respective fibers of the fiber reinforced polymers of the elastically deformable plate 11 a are at least essentially oriented with +/ ⁇ 15° with respect to the longitudinal axis 5 f of the elastic torsion element 5 d.
  • the first dominant fiber direction 12 a crosses the second dominant fiber direction 12 b in a predetermined fiber direction crossing region 14 .
  • the integrated elastic lead-lag hinge 4 of the elastic torsion element 5 d is formed at the predetermined fiber direction crossing region 14 .
  • the integrated elastic lead-lag hinge 4 is formed by a narrowest cross-section area of the elastic torsion element 5 d .
  • this narrowest cross-section is formed by the predetermined fiber direction region 14 .
  • the elastic torsion element 5 d is only illustrated partly in FIG. 2 for clarity and simplicity of the representation, in order to illustrate a preferred configuration of the integrated elastic lead-lag hinge 4 .
  • the integrated elastic lead-lag hinge 4 is illustratively arranged in an associated elastic lead-lag hinge are 13 a of the elastic torsion element 5 d .
  • the latter preferably also comprises an optional elastic flapping hinge area 13 b and a rotor blade attachment area 13 c , i.e. a transition zone 13 c to a respective aerodynamic profile.
  • FIG. 3 shows the elastic torsion element 5 d of FIG. 2 with the longitudinal axis 5 f and the elastically deformable plate 11 a .
  • the elastic torsion element 5 d is only partly illustrated by means of the elastic lead-lag hinge area 13 a , where the integrated elastic lead-lag hinge 4 of FIG. 2 is located.
  • the elastic flapping hinge area 13 b and the rotor blade attachment area or transition zone to an associated aerodynamic profile 13 c are, similar to FIG. 2 , not illustrated in greater detail.
  • the elastic torsion element 5 d is now shown as full laminate 21 including the dominant uninterrupted fibers as described above with reference to FIG. 2 , as well as interrupted fibers and spliced plies. These interrupted fibers and spliced plies preferably round off sharp corners, create smooth transitions, increase a respective in-plane shear strength, and avoid excessively low thicknesses of the elastic torsion element 5 d . Accordingly, in contrast to the partial laminate 20 of FIG. 2 , the full laminate 21 of FIG. 3 is illustrated with respectively rounded edges.
  • the elastic torsion element 5 d and, illustratively, the elastically deformable plate 11 a now comprises an opening 11 i .
  • this opening 11 i is optional and not mandatory, so that this opening 11 i can likewise be omitted.
  • FIG. 4 shows the elastic torsion element 5 d with the longitudinal axis 5 f of FIG. 3 for further illustrating the multiplicity of elastically deformable plates 11 of FIG. 3 .
  • the multiplicity of elastically deformable plates 11 preferably comprises at least two and, preferentially, four elastically deformable plates 11 a , 11 b , 11 c , 11 d.
  • the elastically deformable plate 11 a and, preferably, each one of the elastically deformable plates 11 a , 11 b , 11 c , 11 d exhibits at least approximately an arc-shaped, i.e. curved cross-section.
  • each one of the elastically deformable plates 11 a , 11 b , 11 c , 11 d exhibits this at least approximately arc-shaped cross-section at least in an associated elastic lead-lag hinge area ( 13 a in FIG. 2 and FIG. 3 ) of the integrated elastic lead-lag hinge 4 , as illustrated in FIG. 4 .
  • each one of the elastically deformable plates 11 a , 11 b , 11 c , 11 d is at least partly U-shaped.
  • the elastically deformable plates 11 a , 11 b form illustratively upper deformable plates, while the elastically deformable plates 11 c , 11 d illustratively form lower deformable plates, both with respect to the longitudinal axis 5 f of the elastic torsion element 5 d .
  • the lower elastically deformable plates 11 c , 11 d are arranged in reflection symmetry to the upper elastically deformable plates 11 a , 11 b.
  • FIG. 5 shows the elastically deformable plates 11 a , 11 b , 11 c , 11 d of the multiplicity of elastically deformable plates 11 of FIG. 4 of the integrated elastic lead-lag hinge 4 of FIG. 3 .
  • the elastically deformable plates 11 a , 11 b , 11 c , 11 d are in contrast to FIG. 4 now illustrated in a location that is closer to the elastic flapping hinge area 13 b of FIG. 3 .
  • each one of the elastically deformable plates 11 a , 11 b , 11 c , and 11 d is less curved than in FIG. 4 . Furthermore, each one of the elastically deformable plates 11 a , 11 b , 11 c , 11 d now comprises a dominant fiber direction overlapping area 15 a , where the dominant fiber directions 12 a , 12 b of FIG. 2 overlap each other, as well as single dominant fiber direction areas 15 b , 15 c . In other words, when looking at FIG. 5 in combination with FIG.
  • the arc-shaped cross-section of the elastically deformable plates 11 a , 11 b , 11 c , 11 d is flattened with respect to FIG. 4 , as described above. According to one aspect, this flattening continues in direction of the elastic flapping hinge area 13 b of FIG. 3 .
  • the integrated elastic lead-lag hinge 4 preferably transitions along the longitudinal axis 5 f of the elastic torsion element 5 d from the elastic lead-lag hinge area 13 a of FIG. 3 towards the elastic flapping hinge area 13 b of FIG. 3 from the arc-shaped cross-section into a flat cross-section.
  • the arc-shaped cross-section of the elastically deformable plates 11 a , 11 b , 11 c , 11 d in the elastic lead-lag hinge area 13 a of FIG. 3 of the integrated elastic lead-lag hinge 4 preferably transitions along the longitudinal axis 5 f of the elastic torsion element 5 d towards the rotor blade attachment area or transition zone 13 c of FIG. 3 into a flat cross-section. It should be noted that this is exemplarily further illustrated in FIG. 11 .
  • FIG. 6 shows the elastic torsion element 5 d of FIG. 2 , i.e. the partial laminate 20 of uninterrupted fibers that follow the dominant fiber directions 12 a , 12 b of FIG. 2 .
  • selected fibers of the fiber reinforced polymers that form the elastically deformable plate 11 a are according to one aspect now arranged along at least one third dominant fiber direction 12 c .
  • This at least one third dominant fiber direction 12 c preferably crosses the other two dominant fiber directions 12 e , 12 b , preferentially in the fiber direction crossing region 14 of FIG. 2 .
  • FIG. 7 shows the elastic torsion element 5 d according to FIG. 6 .
  • the elastic torsion element 5 d is now illustrated as full laminate 21 with the dominant uninterrupted fibers that are arranged along the three dominant fiber directions 12 a , 12 b , 12 c of FIG. 6 .
  • the full laminate 21 also comprises interrupted fibers and spliced plies, which round off respective sharp corners, create smooth transitions, increase a respective in-plane shear strength of the elastic torsion element 5 d , and avoid excessively low thicknesses thereof.
  • FIG. 8 shows the multiplicity of elastically deformable plates 11 of FIG. 6 and FIG. 7 , or of FIG. 2 and FIG. 3 , according to a variant with only three elastically deformable plates, i.e. the elastically deformable plates 11 a , 11 d of FIG. 4 , and an additional elastically deformable plate 11 e .
  • the elastically deformable plates 11 a , 11 b are illustratively embodied according to FIG. 4 and arranged in reflection symmetry.
  • the elastically deformable plate 11 e is according to one aspect arranged between the elastically deformable plates 11 a , 11 d.
  • the elastically deformable plate 11 e exhibits a point symmetric cross-section, preferentially at least in the elastic lead-lag hinge area 13 a of FIG. 2 , FIG. 3 , FIG. 6 and FIG. 7 . More specifically, the elastically deformable plate 11 e exemplarily defines a rectangular cross-section.
  • FIG. 9 shows the elastic torsion element 5 d of FIG. 8 with the elastically deformable plates 11 a , 11 d .
  • the elastically deformable plate 11 e of FIG. 8 with the rectangular cross-section is now exemplarily replaced by an elastically deformable plate 11 f , which is still point symmetric, but illustratively exhibits at least approximately an S-shaped cross-section in the elastic lead-lag hinge area 13 a of FIG. 2 , FIG. 3 , FIG. 6 and FIG. 7 .
  • FIG. 10 shows the elastic torsion element 5 d of FIG. 4 with the multiplicity of elastically deformable plates 11 that comprises the elastically deformable plates 11 a , 11 b , 11 c , 11 d of FIG. 4 .
  • the elastically deformable plates 11 a , 11 b , 11 c , 11 d are now rigidly mounted to each other by means of a bolted connection 16 .
  • the bolted connection 16 is formed by means of an exemplary connection bolt 16 a at least in close proximity and, preferably, in the region of the longitudinal axis 5 f of the elastic torsion element 5 d.
  • FIG. 11 shows the elastic torsion element 5 d of FIG. 2 to FIG. 5 with its longitudinal axis 5 f and with the multiplicity of elastically deformable plates 11 that comprises according to FIG. 4 and FIG. 5 the elastically deformable plates 11 a , 11 b , 11 c , 11 d .
  • the elastic torsion element 5 d is again only partly shown and illustrated with a direction 18 a that exemplarily points towards the rotor blade attachment area or transition zone 13 c of FIG. 2 and FIG. 3 , as well as a direction 18 b that points towards the elastic flapping hinge area 13 b of FIG. 2 and FIG. 3 .
  • the elastically deformable plates 11 a , 11 b are now preferably integrated into a single slotted elastically deformable plate 11 g . More specifically, according to one aspect the elastically deformable plates 11 a , 11 b are at least partly separated in the single slotted elastically deformable plate 11 g by means of an associated separating gap or slot 17 a .
  • This associated separating gap or slot 17 a is preferably at least provided in the elastic lead-lag hinge area 13 a of the elastic torsion element 5 d , i.e. at the integrated elastic lead-lag hinge 4 thereof.
  • the associated separating gap or slot 17 a is only provided in a central portion of the elastic lead-lag hinge area 13 a , i.e. preferably not in transition regions towards the rotor blade attachment area or transition zone 13 c of FIG. 2 and FIG. 3 , as well as towards the elastic flapping hinge area 13 b of FIG. 2 and FIG. 3 .
  • the elastically deformable plates 11 c , 11 d are preferably integrated into a single slotted elastically deformable plate 11 h . More specifically, according to one aspect the elastically deformable plates 11 c , 11 d are at least partly separated in the single slotted elastically deformable plate 11 h by means of an associated separating gap or slot 17 b .
  • This associated separating gap or slot 17 b is preferably also at least provided in the elastic lead-lag hinge area 13 a of the elastic torsion element 5 d , i.e. at the integrated elastic lead-lag hinge 4 thereof.
  • the associated separating gap or slot 17 b is only provided in a central portion of the elastic lead-lag hinge area 13 a , i.e. preferably not in transition regions towards the rotor blade attachment area or transition zone 13 c of FIG. 2 and FIG. 3 , as well as towards the elastic flapping hinge area 13 b of FIG. 2 and FIG. 3 .
  • a cut view of the central section of the elastic lead-lag hinge area 13 a is shown in enlarged form in a detail view 19 a .
  • a further enlarged cut view 19 b is also shown.
  • the two upper elastically deformable plates 11 a , 11 b of FIG. 4 may be replaced with the single slotted elastically deformable plate 11 g of FIG. 11 .
  • the two lower elastically deformable plates 11 c , 11 d of FIG. 4 may be replaced with the single slotted elastically deformable plate 11 h of FIG. 11 .
  • the slotted elastically deformable plates 11 g , 11 h of FIG. 11 may be attached to each other by means of the bolted connection 16 according to FIG. 10 .
  • the flat elastically deformable plate 11 e of FIG. 8 can be introduced between the slotted elastically deformable plates 11 g , 11 h of FIG. 11 .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
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US16/143,774 2017-10-12 2018-09-27 Elastic torsion element for connecting a rotor blade to a rotor hub of a rotor Active 2039-03-07 US10829214B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP17400057 2017-10-12
EP17400057.0A EP3470333B1 (fr) 2017-10-12 2017-10-12 Élément de torsion élastique permettant de relier une pale de rotor à un moyeu de rotor d'un rotor
EP17400057.0 2017-10-12

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US20190112040A1 US20190112040A1 (en) 2019-04-18
US10829214B2 true US10829214B2 (en) 2020-11-10

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Citations (7)

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Publication number Priority date Publication date Assignee Title
US5263821A (en) 1991-01-15 1993-11-23 United Technologies Corporation Mid-beam jointed reconfigurable bearingless main rotor assembly
EP1431176A1 (fr) 2002-12-03 2004-06-23 Fuji Jukogyo Kabushiki Kaisha Bras de flexion pour rotor d'hélicoptère
CA2650760A1 (fr) 2008-01-25 2009-07-25 Eurocopter Pale de giravion munie d'un longeron integrant une attache de fixation, et procede de fabrication d'un tel longeron
US20100278648A1 (en) 2009-04-29 2010-11-04 Eurocopter Deutschland Gmbh Tension-torque-transmission element for a fenestron blade and method for producing it
US8821128B2 (en) 2010-02-26 2014-09-02 Airbus Helicopters Blade with adaptive twisting, and a rotor provided with such a blade
EP2832640A1 (fr) 2013-08-02 2015-02-04 Bell Helicopter Textron Inc. Flexion composite pour système de rotor basculant
US20150158582A1 (en) 2013-12-10 2015-06-11 Airbus Helicopters Deutschland GmbH Beam for a rotorcraft rotor and rotorcraft rotor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5263821A (en) 1991-01-15 1993-11-23 United Technologies Corporation Mid-beam jointed reconfigurable bearingless main rotor assembly
EP1431176A1 (fr) 2002-12-03 2004-06-23 Fuji Jukogyo Kabushiki Kaisha Bras de flexion pour rotor d'hélicoptère
US6805948B2 (en) * 2002-12-03 2004-10-19 Fuji Jukogyo Kabushiki Kaisha Flexbeam
CA2650760A1 (fr) 2008-01-25 2009-07-25 Eurocopter Pale de giravion munie d'un longeron integrant une attache de fixation, et procede de fabrication d'un tel longeron
US8061991B2 (en) 2008-01-25 2011-11-22 Eurocopter Rotorcraft blade provided with a spar incorporating a fastener attachment, and a method of fabricating such a spar
US20120031544A1 (en) 2008-01-25 2012-02-09 Eurocopter Method of fabricating a spar for a rotorcraft blade
US8591197B2 (en) 2008-01-25 2013-11-26 Eurocopter Method of fabricating a spar for a rotorcraft blade
US20100278648A1 (en) 2009-04-29 2010-11-04 Eurocopter Deutschland Gmbh Tension-torque-transmission element for a fenestron blade and method for producing it
US8821128B2 (en) 2010-02-26 2014-09-02 Airbus Helicopters Blade with adaptive twisting, and a rotor provided with such a blade
EP2832640A1 (fr) 2013-08-02 2015-02-04 Bell Helicopter Textron Inc. Flexion composite pour système de rotor basculant
US20150158582A1 (en) 2013-12-10 2015-06-11 Airbus Helicopters Deutschland GmbH Beam for a rotorcraft rotor and rotorcraft rotor

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* Cited by examiner, † Cited by third party
Title
European Search Report for European Application No. EP17400057, Completed by the European Patent Office, dated Feb. 24, 2018, 5 pages.

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EP3470333B1 (fr) 2019-12-04
US20190112040A1 (en) 2019-04-18

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